The invention relates generally to linear assembly machines having multiple work stations and product fixtures and more specifically to a reconfigurable linear assembly machine having a plurality of identical support modules which may be selectively installed or removed at locations in the assembly machine to add or remove certain manufacturing processes and assembly steps.
Automated assembly machines may be categorized according to the fundamental physical layout of the machine that is, whether it is rotary or linear. In a typical linear machine, a recirculating belt or chain carries a plurality of product fixtures sequentially and linearly along a plurality of adjacent, stationary work stations. In a rotary machine, the product fixtures are disposed upon a circular, typically horizontal, plate which rotates about a center, vertical axis and presents the fixtures to a plurality of stationary work stations. Numerous considerations such as the number of work stations, the number of product fixtures, the ratio between these two numbers, work station cycle times and other factors influence the decision to select one or the other of these types of machines to fabricate a given product.
A second mode of categorization is temporal rather than physical and relates to whether the product fixtures move simultaneously or independently. In a synchronous machine such as either the linear or rotary assembly machines described above, all product fixtures, since they are coupled together or to a common support, move together. In an asynchronous machine, the product fixtures are independent of one another and may therefore independently circulate between work stations or independently remain stationery at a work station as necessary.
Linear or straight line machines are illustrated in commonly owned U.S. Pat. Nos. 3,039,597 and 4,404,505. A rotary assembly machine is disclosed in commonly owned U.S. Pat. No. 3,143,792.
While these machines provide exceptional control of the manufacturing process by virtue of their repeatability and their close operating tolerances, one difficulty shared by such machines, which is an outgrowth of their basic construction, is their dedication to a given manufacturing process. That is, a certain number of product fixtures and work stations necessary to produce a given product are relatively permanently arranged in such machines and are typically only broken down for repair or rebuilding. Clearly, during the period of repair or rebuilding of just a portion of such machine, the entire machine is unavailable for production. Furthermore, because of the unitary, dedicated construction of such machines, the ability to relatively quickly add or remove a certain process or tool fixture to add or delete a certain process step, is generally unavailable. Nonetheless, it has been found desirable in this general class of machines to have the flexibility of repair, substitution, addition and deletion. The present invention is directed to providing such flexibility in linear assembly machines.